The present invention relates to a respirator mask and specifically to a respirator mask which includes replaceable cartridges and may also include a replaceable exhalation valve.
In the prior art, respirator masks have been made with replaceable cartridges. These respirator masks normally include cartridges being replaceable by either a screw on joint, using threaded connections or using a bayonet type of joint between the cartridge and the mask. In these prior art devices, it is often difficult to replace the cartridge since the threads may become misaligned or the bayonet joint may be difficult to engage. In addition, in the prior art, if the cartridge is not either threaded on properly or connected properly using the bayonet joint, the mask may allow for the leakage of outside unfiltered air into the mask. It is sometimes difficult to tell if the cartridge has been properly seated into the mask, which as indicated above, can allow for a dangerous situation of the mask allowing in unfiltered air.
The prior art masks, using either a screw on cartridge or a bayonet joint between the cartridge and the mask, are also relatively expensive to manufacture since the threaded connections must be accurately dimensioned and the bayonet joint must also be accurately dimensioned to insure a proper seal. Sometimes it is difficult to maintain the proper tolerances during the manufacturing procedures to ensure that the cartridge is properly sealed to the mask and therefore the prior art devices quite often incorporate an additional sealing gasket to ensure that any misalignment will not allow for the introduction of unfiltered air into the interior of the mask. These various difficulties in manufacturing and in the provision of the additional gasket increase the cost of the prior art masks and it would be desirable to both simplify the structure of the mask and also to reduce the overall costs.
The prior art masks normally include an exhalation valve permanently mounted to the exterior of the mask. Generally, once these exhalation valves are attached to the mask as part of the manufacturing operation they cannot be removed and if the exhalation valve is damaged, the valve cannot be replaced and the mask must be discarded. In addition, the use of the exhalation valve and the exterior position makes the mask more bulky and cumbersome in design.